Browsing by Subject "Nanopillars"

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    ItemOpen Access
    Light extraction efficiency enhancement of colloidal quantum dot light-emitting diodes using large-scale nanopillar arrays
    (Wiley-VCH Verlag, 2014) Yang, X.; Dev, K.; Wang, J.; Mutlugun, E.; Dang, C.; Zhao Y.; Liu, S.; Tang, Y.; Tan S.T.; Sun, X. W.; Demir, Hilmi Volkan
    A colloidal quantum dot light-emitting diode (QLED) is reported with substantially enhanced light extraction efficiency by applying a layer of large-scale, low-cost, periodic nanopillar arrays. Zinc oxide nanopillars are grown on the glass surface of the substrate using a simple, efficient method of non-wetting templates. With the layer of ZnO nanopillar array as an optical outcoupling medium, a record high current efficiency (CE) of 26.6 cd/A is achieved for QLEDs. Consequently, the corresponding external quantum efficiency (EQE) of 9.34% reaches the highest EQE value for green-emitting QLEDs. Also, the underlying physical mechanisms enabling the enhanced light-extraction are investigated, which leads to an excellent agreement of the numerical results based on the mode theory with the experimental measurements. This study is the first account for QLEDs offering detailed insight into the light extraction efficiency enhancement of QLED devices. The method demonstrated here is intended to be useful not only for opening up a ubiquitous strategy for designing high-performance QLEDs but also with respect to fundamental research on the light extraction in QLEDs.
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    ItemOpen Access
    A motion-and sound-activated, 3D-printed chalcogenide-based triboelectric nanogenerator
    (Wiley-VCH Verlag, 2015) Kanik, M.; Say, M. G.; Daglar, B.; Yavuz, A. F.; Dolas, M. H.; El-Ashry, M. M.; Bayındır, Mehmet
    A multilayered triboelectric nanogenerator (MULTENG) that can be actuated by acoustic waves, vibration of a moving car, and tapping motion is built using a 3D-printing technique. The MULTENG can generate an open-circuit voltage of up to 396 V and a short-circuit current of up to 1.62 mA, and can power 38 LEDs. The layers of the triboelectric generator are made of polyetherimide nanopillars and chalcogenide core-shell nanofibers.
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    ItemOpen Access
    Strong nonradiative energy transfer from the nanopillars of quantum wells to quantum dots: Efficient excitonic color conversion for light emitting diodes
    (Optical Society of America, 2012) Güzeltürk, Burak; Nizamoglu, Sedat; Jeon, D. -W.; Lee, I. -H.; Demir, Hilmi Volkan
    Efficient nonradiative energy transfer is observed from nanopillars of InGaN/GaN quantum wells to colloidal CdSe/ZnS quantum dots up to 83% efficiency. Nanostructured architecture is shown to promote excitonic color conversion for LED applications. © OSA 2012.